1. Field of the Invention
The present invention is directed to a folding stage and in particular, to an elevationally adjustable mobile folding stage with improved folding and stability.
2. Prior Art
Folding stages are used for a variety of purposes to provide a temporary raised platform for use in schools, hotels, convention centers and other institutions or multiple use facilities requiring the capability of setting up temporary stages. Such stages may be positioned adjacent one another to form an extended stage surface or positioned to support bridging decks between the stages to form an extended stage surface. When not in use, the stages have a framework that folds to compact dimensions for storage. The stages typically have two stage decks hinged together along a center line to provide folding action and have legs that remain substantially vertical when the stage decks fold. An example of such a folding stage is shown in U.S. Pat. No. 5,325,640 to Luedke et al., issued Jul. 5, 1994, assigned to Sico, Incorporated, the Assignee of the present invention. Although the Luedke et al. patent is very successful in providing useful and efficient folding stages, further improvements are still possible, particularly with regard to stages that fold from the use position to a storage position, with the underside of the stages substantially opposing one another in the folded storage position.
To provide elevationally adjustable stages, the legs of the stage framework must be able to telescope to adjust the height of the stage decks. As the elevational adjustment increases, the distance that the inner leg must nest into the outer leg increases. As the distance increases, the likelihood that the legs will bind or loosen, especially with use over time, increases. Therefore, it is necessary to provide spacing that provides a sturdy leg structure with little freedom between the telescoping leg members to eliminate wobble. At the same time, it is important that the spacer assembly provide for the telescoping leg members to slide easily relative to one another.
A common problem with folding stages that increases over time is the adjustment of the stage to ensure that the decks remain substantially aligned and horizontal in the unfolded use position. Prior stages, as shown in U.S. Pat. No. 5,325,640 to Luedke et al., utilize a bolt in the center joint area of the stage. The bolt acts as a step where the two deck frameworks come together along the folding line. Adjustment of the stop adjusts the relative position of the frame and the decks. These types of stages use a spacing linkage to apply tension on the stage folding linkage and take up any looseness that would allow the stage to rock or shift. As this linkage passes through a toggle position to a locked position, the decks are folded to a slightly concave alignment before they revert back to level. At this point, the leveling bolt acts as a spring with an extremely high spring constant that must be compressed before it can return to the level position. Although this configuration does provide alignment, it does not provide much compression, forcing other portions of the linkage to have some looseness in order to allow the linkage to pass through the toggle position. Over time, the components may wear, changing alignment so that the bracing of the framework is less rigid and has more play. This condition results in a stage feeling less solid in the unfolded use position.
It can be seen then that a new and improved stage is required that overcomes the problems of the prior art. The spacer assembly for the telescoping legs should provide a snug fit that does not loosen or bind over time and that provides for easy sliding and adjustment of the telescoping legs. An improved stage should provide a locking and spacing mechanism that can be easily adjustable and that does not cause other components to loosen and lead to wobbling and a less sturdy stage. The present invention addresses these as well as other problems associated with elevationally adjustable folding stages.